1. Field of the Invention
The present invention relates generally to the field of conveyors, such as those used in the manufacture of cans and bottles. More specifically, the present invention discloses a pusher bar apparatus used to remove containers from a splice plate between adjacent conveyors.
2. Statement of the Problem
Conveyor lines are widely used, for example, in the beverage industry to transport containers, such as cans or bottles, within production facilities. Conveyor lines normally incorporate a sequence of stations for performing the various steps in manufacturing and filling containers. It is advantageous not to have to shut down the entire line if one of these stations breaks down or is otherwise taken off-line. This is conventionally accomplished by providing wide bi-directional conveyors between stations for temporary storage of containers, as shown generally in FIGS. 1 and 2. Each bi-directional conveyor 20 is typically mounted perpendicular to the main conveyor 10, with a splice plate 25 mounted to cover the gap between the conveyors 10, 20. If a downstream station goes off-line, containers will begin to accumulate on the main conveyor 10 until the back-up is detected by an optical sensor 16. This triggers the bi-directional conveyor 20 to run in the reverse direction (i.e., away from the main conveyor 10). The back-up of containers eventually builds to the point where containers overflow from the main conveyor 10, over the splice plate 25, and onto the bi-directional conveyor for temporary storage.
The process is reversed when the downstream station goes back on-line. A second sensor 14 detects when the main conveyor 10 has cleared to a point where the bi-directional conveyor 20 can reverse direction (i.e., toward the main conveyor 10) and begin to release stored containers back onto the main conveyor 10. A third sensor 24 detects when the bi-directional conveyor 20 has been emptied and shuts down the bi-directional conveyor 20. Any containers on the splice plate will normally stay there unless manually removed.
Governmental regulations and industry standards prohibit manufacturers from using containers that have been exposed to air-borne contaminants for extended periods of time. As a result, the normal practice in the beverage industry has been to discard or recycle any containers left standing on the splice plate at the end of the storage cycle. The splice plate is typically 16 to 18 feet long and 6 to 8 inches wide. Conventional beverage cans can be packed to a density of 22 cans per square foot. The storage cycle typically occurs about six times per hour in a conventional can line. Therefore, a substantial number of cans are needlessly discarded. Although the individual cost of each container may be only a few cents, the total cost of wasted cans over an extended period of months or years can be quite substantial. The environmental costs associated with recycling cans should also be considered in addition to the purely economic costs. Recycled cans are resmelted, which consumes natural resources in terms of fuel and electricity, and generates pollutants. Other types of containers are more difficult to recycle and are sometimes disposed of in landfills.
Pusher bars and other types of movable guides have been used in association with conveyor systems in the past in a wide variety of other applications, including the following:
______________________________________ Inventor Patent No. Issue Date ______________________________________ Wolfe et al. 3,442,401 May 6, 1969 Donner 3,465,868 Sept. 9, 1969 Chalich 3,669,241 June 13, 1972 ______________________________________
Chalich discloses a conveyor system that uses a bi-directional accumulating conveyor 20 for temporary storage of packages (e.g. bottles). The accumulating conveyor 20 includes a package stabilizing rail 61 to help maintain the packages in a desired orientation on the accumulating conveyor. The stabilizing rail 61 automatically moves with the accumulating conveyor 20 between two extreme positions as bottles are accumulated and then released to the main conveyor. The stabilizing rail 61 "is overlying the dead plate 28" (col. 7, lines 36-37) when all of the bottles have been returned to the chain conveyor 10. This suggests that the stabilizing rail serves to push the last bottles from the accumulating conveyor 20 over the dead plate (or splice plate) 28 and onto the main conveyor 10. However, the Chalich device uses an entirely different mechanism to accomplish this result. As shown in FIG. 4 of the Chalich patent, the stabilizing rail 61 rides on the accumulating conveyor 20 by means of two endless chains 73, 74 located on either side of the conveyor.
Wolfe et al. disclose equipment for palletizing excess cans from can supply equipment and for depalletizing these cans when later needed by can use equipment. A conveying system permits the movement of cans from the can supply equipment directly to the can use equipment under normal conditions, or to a palletizing station when there is an oversupply of cans from the can supply equipment. The conveying system also permits direct supply from the depalletizing station to the can use equipment when necessary. A can sweeping means 96 and can holding means 98 have downwardly-extending fingers 100 and 102 that are employed to advance groups of cans from the carriage 90 at the end of the conveyor 40 onto pallets 46 in the pallet zone 44. This process is reversed to depalletize containers.
Donner discloses an apparatus for forming a single-file column of bottles on an output conveyor. A combination backstopping bar and bottle guide 45 is movably mounted to relieve bottle jams that might occur when the bottles are formed into a single-file column.
3. Solution to the Problem
None of the prior art references uncovered in the search show a motor-drive pusher bar system for automatically pushing any containers left on the splice plate onto the main conveyor at the end of each storage cycle. This substantially eliminates the problems associated with wasted containers, as described above.